1. Field of the Invention
The invention relates generally to a load relief coupling for interconnecting and adjustably changing the distance of separation of two members of a supporting apparatus and, more specifically, to a load relief coupling device which interconnects a lower, supporting member and an upper, supported member of a concrete forming apparatus to permit quick and easy relief of the load on the members by a formed concrete structure.
2. Background of the Prior Art
Concrete forming apparatus is in wide use in the construction of buildings, bridges, and other concrete structures. The formwork against which the concrete is formed is often held in place by shoring apparatus. In forming horizontal concrete building sections, such as floors and the like, the substantially horizontally disposed formwork is supported on a plurality of vertical support members which are capable of withstanding the applied load of uncurred concrete poured upon the formwork. Once the poured concrete has set to a sufficient degree, the formwork is stripped from the concrete structure. Whether the concrete structure is substantially vertical or horizontal, or virtually any other orientation, it is frequently found that a substantial force is exerted by the formed concrete structure against the formwork and hence the structural members which support the formwork. By way of example, if the poured concrete structure is a horizontally disposed floor or ceiling, a significant proportion of the weight of the concrete structure will bear against the formwork and hence against the support members. Accordingly, in order to strip the formwork away from the poured concrete structure, it is necessary to reduce the vertical extension of the support members so as to be able to lower the formwork.
In the prior art, the formwork is commonly supported by a lower support member which supports an upper, supported member that is interconnected to the supporting member by a wing nut or the like. The wing nut is rotated relative to threads in the supporting and/or supported member to move the supporting and supported member relative to each other so as to reduce the vertical height of the support member and move the formwork away from the poured concrete structure. The load on the support member by the poured concrete structure, however, makes it extremely difficult to loosen the wing nut. It is common for workers to overcome this resistance by extending the lever arm for moving the wing nut by using a section of pipe connected to the wing nut and then either hammering on the pipe in order to forcibly move the wing nut or, in more difficult circumstances, using a fork lift or other powered device to push against the pipe and thereby forcefully rotate the wing nut to strip the formwork from the formed concrete structure. This way of stripping the formwork has several disadvantages. It is difficult for a single laborer to accomplish, it often requires the use of ancillary equipment, and it requires the exertion of extremely high forces on the support members.
The invention consists of a load relief coupling for interconnecting and adjustably changing the distance of separation of a lower supporting member and an upper supported member that are used to hold in position formwork of a concrete form apparatus. The lower supporting member and the upper supported member are moveable relative to each other along their common axis so as to increase or decrease their relative separation. The load relief coupling of the present invention is interposed between the supporting member and the supported member. In the load position, the load relief coupling has a pre-selected, increased width dimension and is quickly and easily adjusted to a released, decreased width configuration which releases the load interposed on the supporting member by the supported member.
The load relief coupling includes three members which in the preferred embodiment, have an annular ring structure. A lower, supported annular ring is in contact engagement with the supporting member and includes an opposing surface having a plurality of circumferentially teeth arranged which project in an upward direction. A second supporting annular ring includes a surface that is in contact engagement with the supported member and an opposing surface having a plurality of teeth arranged circumferentially and which project downwardly. The third annular ring is an inner annular ring that is positioned between the supporting and supported annular rings and includes a plurality of circumferentially arranged teeth which project in opposing arrangement and which are positioned to engage the corresponding teeth on the supporting and supported annular rings.
Each of the annular rings has a radially extended arm. A connector, such as a nut and bolt combination, is used to position the radially extended arm of the supporting member and the radially extended arm of the supported member in a pivoted position relative to the radially extended arm of the inner annular ring so that the mating teeth of the annular ring structures support or move the outer annular rings relative to inner annular ring to a loaded position wherein the outer annular rings are separated from each other and the inner annular ring by a pre-selected, large distance. Release of the connecting member will allow the teeth of the outer annular rings to move relative to the teeth of the inner annular ring, collapsing the two outer annular rings toward the inner annular ring, thereby reducing the combined width dimension of the load relief coupling. Accordingly, when used in an assembly with the lower, supporting member and the upper, supported member, release of the connector will reduce the relative separation distance of the supporting and supported member, thus relieving a substantial portion of the load on the support assembly so that the wing nut can be easily rotated by a single laborer to allow the supported formwork to be stripped away from the poured concrete structure.
In the preferred embodiment, the coacting teeth of the annular rings have a self-centering structure which helps to maintain the coaxial arrangement of the annular rings in the load relief coupling assembly. In particular, the teeth of inner annular ring have a helical chevron radial cross-section and the teeth of the outer annular ring have a corresponding, mating helical radial cross-section so that the teeth of the outer annular rings remain centered relative to the teeth of the inner annular ring.
An object of the present invention is to provide a load relief coupling for quickly reducing the relative separation distance of a supporting member and supported member which it interconnects.
Another object of the present invention is to provide a coupling which quickly and easily reduces the load between two support members of a support apparatus to allow removal of the support apparatus.
A further object of the present invention is to provide a quick load relief coupling that interconnects support members of a support apparatus for concrete formwork which permits quick and easy stripping of supported concrete formwork after the concrete has sufficiently cured.
These and other objects of the invention will be made apparent upon a review and understanding of this specification, the associated drawings, and the appended claims.